The invention relates to a vertical tubular bagging machine comprising a strip of foil, a storage roller, guide rollers to guide the flat strip of foil to a forming shoulder, a foil-removing means to transport the strip of foil, a vertically aligned fill pipe to receive the strip of foil which has been reshaped into a foil tube, jaws of a cross-welding device to create cross-seams, a separating device to cut the foil tube, and plural flat expanding elements connected to the fill pipe and projecting away from the fill pipe, and an edge-welding device per expanding element is provided in foil-transport direction arranged downstream of the expanding elements, each edge-welding device being directed against the tube edge deflected by each expanding element. The invention relates furthermore to a bag created with such a tubular bagging machine.
Such a known tubular bagging machine is used to manufacture tubular bags, the four edges of which are welded. These tubular bags are relatively stable. The otherwise centrally extending longitudinal seam of the bag is located at an edge of the bag by an asymmetrical forming shoulder so that a separate longitudinal seam no longer exists. In another known tubular bagging machine, a centrally arranged longitudinal seam of the bag is created by means of a symmetrical forming shoulder. The edges of the bag are separately welded so that a bag has five longitudinally extending welding seams.
Whereas a bag with merely four vertically extending welding seams does not have a longitudinal seam, which interferes with the printing on the bag, a common, symmetrical forming shoulder can be used for the manufacture of a bag with a center longitudinal seam.
The known bags have the disadvantage that they have a relatively square shape with an approximately center point of gravity. They are thus not suited for packaging of certain products, for which a relatively high bag with a relatively low center of gravity is desired.
The basic purpose of the invention is to provide a vertical tubular bagging machine of the above-described type and a bag manufactured therewith so that bags with vertical, welded edges are created in a manner which has, for the purpose of a good stability, a relatively low center of gravity.
The vertical tubular bagging machine of the invention has on the one side of the fill pipe only one edge-welding device to create a top seam and on the opposite side of the fill pipe two edge-welding devices to create two bottom seams of a bag. The bag manufactured by means of such a tubular bagging machine has as a special feature this top seam and these bottom seams.
The invention has the advantage that a bag stabilized in vertical direction is achieved, the center of gravity of which is relatively low. The cross-welding device produces two welding seams per bag which extend in vertical direction and stabilize the bag in this direction. The low center of gravity is achieved by providing two bottom seams and only one top seam. The two bottom seams result, because of their distance from one another, in a relatively wide bottom of the bag, whereas the one top seam enables the bag to converge pointed at the top. The bag on the vertical tubular bagging machine is filled through an opening which, after the bag has been filled, is closed off by a vertically aligned welding seam.
When a device for changing the distance between the edge-welding devices and/or a device for changing the distance between the expanding elements is provided on the two edge-welding devices on the opposite side, then this accomplishes several advantages. A change of the distance between the edge-welding devices results in a change of the distance between the bottom seams. Thus it is easily possible to change the thickness of the bag in the area of its bottom seams. A change of the distance between the edge-welding devices serves to adjust to a different fill pipe having a different cross section in order to manufacture bags with different widths. When both the distance between the expanding elements and also the distance between the edge-welding devices are changed, it is easily possible to adjust the tubular bagging machine to the production of bags with a changed width and bottom-side thickness.
When the forming shoulder is an asymmetrical forming shoulder with two differently long collar front parts, it is possible to place a vertically extending seam for closing of the foil tube parallel to its transport device into the top seam or one of the bottom seams of the bag. Such a seam has the advantage that a side surface of the bag, and there in particular the printing, is not hindered by a further seam.
An air intake on an expanding element for the purpose of sucking in the foil has the advantage that a foil deflection occurs in this manner in order to create a foil edge. The deflected foil is guided over the expanding element. The edge welding occurs in the area of the expanding element.
The tubular bagging machine can be operated continuously or in cycles. The foil is removed accordingly. Sealing bands, which rotate to weld the edges, and a rotating system of cross-jaws are suited for a continuous operation. Hot-sealing jaws, which are cyclically operated, can be used in a cycled operation.
When a device for mounting of an edge reinforcement, in particular a foil or metal strip, is provided on the flat strip of foil, and when this edge reinforcement is intended for entry into an edge to be welded, then it is possible to reinforce one edge of the bag in order to increase in this manner the stability of the bag. The two edges at the bottom of the bag are reinforced when one device is provided for both edge-welding devices on the opposite side. A stable bottom secures in a relatively good manner the outer shape of the bag.